The present invention relates to a scanning probe microscope comprising a cantilever having a minute probe at one end thereof, a laser radiating laser beams to a laser beam reflecting surface of the cantilever, an optical position sensor detecting positions of reflected laser beams, specimen moving means moving a specimen, and cantilever oscillating means periodically oscillating the cantilever with a predetermined amplitude. The scanning probe microscope performs a first operation in which if the optical position sensor detects a reduced amplitude when the probe of the cantilever comes into contact with the specimen, uneven surface state data of the specimen are obtained on the basis of a control amount of upward and downward movements of the specimen moving means which is moved upward or downward in order to maintain the reduced amplitude constant, and a second operation in which physical action force data of the specimen are obtained by keeping the probe spaced from the specimen by a predetermined amount on the basis of the uneven surface state data obtained by the first operation.
In the related arts a scanning probe microscope comprises a cantilever having a minute probe at one end thereof, a laser radiating laser beams to a laser beam reflecting surface of the cantilever, an optical position sensor detecting positions of reflected laser beams, specimen moving means moving a specimens and cantilever oscillating means periodically oscillating the cantilever with a predetermined amplitude. The scanning probe microscope performs a first operation in which if the optical position sensor detects a reduced amplitude when the probe of the cantilever comes into contact with the specimen, uneven surface state data of the specimen are obtained on the basis of a control amount of upward and downward movements of the specimen moving means which is moved upward or downward in order to maintain the reduced amplitude constant, and a second operation in which physical action force data of the specimen are obtained by keeping the probe spaced from the specimen by a predetermined amount on the basis of the uneven surface state data obtained by the first operation. In the first operation, the cantilever is oscillated by applying a frequency near a resonant point of the dependent curve (Q-curve) of the cantilever oscillating frequency and the amplitude. In the second operation, physical operation data of the specimen are obtained by keeping the probe spaced by a predetermined extent from the specimen on the basis of the uneven surface state data obtained by the first operation.
The scanning probe microscope further comprises a phase sensor, which detects a signal generated in response to a time delay (phase) in the oscillation of the cantilever caused by interactions of the specimen surface and the probe. The scanning probe microscope measures differences in physical properties of the specimen surface on the basis of a phase measured near a resonance point of the Q-curve.
With the scanning probe microscope of the related art, the cantilever oscillating frequency is set near the resonance point of the dependent curve (Q-curve) of the cantilever oscillating frequency and amplitude during the first operation, Therefore, the cantilever is quickly oscillated but is slow to damp. Specifically, even when it is subject to the interaction of the specimen, the probe takes time to damp, and does not make its amplitude variation constant immediately. This will lead to a delay in the control operation of the specimen moving means, and an operation amount of the specimen moving means is determined with a delay. Data concerning uneven states of the specimen cannot be accurately obtained on the basis of the control amount of the specimen moving means. It is also possible to accelerate the upward and downward movements of the specimen moving means. However, there is a problem of an oscillation phenomenon in which a direction of amplitude variations and control of the upward and downward movements are not in agreement. Specifically, since there is no air resistance in a a vacuum, the cantilever is difficult to damp, and it takes time to reach the target amplitude when there is interaction with a specimen. This means that the control operation is further delayed, and that uneven surface states of the specimen cannot be measured.
In the second operation, the probe is kept spaced from the specimen on the basis of the uneven surface state data obtained in the first operation, However, since the uneven surface state data are not accurately obtained, it is not possible to obtain physical property data with the probe spaced from the specimen.
The present invention is intended to facilitate, in a first operation, damping transient oscillation variations of the cantilever probe coming into contact with the specimen by setting opposite sides of a frequency band, which is a half value of a dependent curve (Q-curve) of a cantilever oscillating frequency and amplitude, as a cantilever oscillating frequency, and by keeping the cantilever oscillating frequency far from an oscillating frequency (near a resonance point) where the cantilever is slow to damp. Specifically, the invention aims at performing measurements in a vacuum where there is no air resistance. Further, in the second operation, the probe is maintained accurately spaced with a predetermined extent from the specimen surface on the basis of the uneven surface state data obtained in the first operation, so that physical properties of the specimen surface can be accurately measured.
In order to overcome the foregoing problems, the present invention is intended to facilitate, in a first operation, damping transient oscillation variations of the cantilever probe coming into contact with a specimen by setting opposite sides of a frequency band, which is a half value of a dependent curve (Q-curve) of a cantilever oscillating frequency and amplitude, as a cantilever oscillating frequency, and by keeping the cantilever oscillating frequency far from an oscillating frequency (near a resonance point) where the cantilever is slow to damp. Specifically, the invention aims at performing measurements in a vacuum where there is no air resistance. Further, in the second operation, the probe is maintained accurately spaced with a predetermined extent from the specimen surface on the basis of the uneven surface state data obtained in the first operation, so that physical properties of the specimen surface can be accurately measured.